Wednesday, April 19, 2006
Kind of a Reverse Typhoid Mary
Salome Simon, a prostitute in Nairobi, Kenya, has had unprotected sex with probably 50,000 men over the last 20 years in a nation with perhaps a 25 percent AIDS infection rate. She is not infected.
Despite a near total lack of progress, scientists believe her apparent natural immunity will lead to a vaccine, eventually.
Here's the weird part:
It also seems, bizarrely, that the immunity fades if sexual activity ceases. Blood tests have shown that women who take a break from their work, as the Nairobi prostitutes often do on their annual return to their villages, suffer a sharp fall in their immune responses. Several have contracted the virus on resuming business. "The conclusion is that they are best protected when their systems are being constantly challenged," says Dr Plummer. "When there is nothing to fight, the defences come down."
Nor is the women's immunity absolute. When HIV is introduced into samples of their blood, it takes hold as it would normally. Perhaps the most astonishing thing about the Nairobi prostitutes is, therefore, that they seem to be protected only against contracting HIV through sex. "This makes us think," says Dr Richard Lester, an infectious disease specialist attached to the team, "that the key to the immunity may lie in their genital tracts. The virus is entering their bodies, but before it gets into their bloodstream it is being identified and killed.
Despite a near total lack of progress, scientists believe her apparent natural immunity will lead to a vaccine, eventually.
Here's the weird part:
It also seems, bizarrely, that the immunity fades if sexual activity ceases. Blood tests have shown that women who take a break from their work, as the Nairobi prostitutes often do on their annual return to their villages, suffer a sharp fall in their immune responses. Several have contracted the virus on resuming business. "The conclusion is that they are best protected when their systems are being constantly challenged," says Dr Plummer. "When there is nothing to fight, the defences come down."
Nor is the women's immunity absolute. When HIV is introduced into samples of their blood, it takes hold as it would normally. Perhaps the most astonishing thing about the Nairobi prostitutes is, therefore, that they seem to be protected only against contracting HIV through sex. "This makes us think," says Dr Richard Lester, an infectious disease specialist attached to the team, "that the key to the immunity may lie in their genital tracts. The virus is entering their bodies, but before it gets into their bloodstream it is being identified and killed.
# posted by Roger Fraley @ 7:50 AM 
